Patent GB-1354929-A (GB)
Title: Drive devices
IPC: F04B47/04
Filed: 1971-12-20
Abstract: 1354929 Controlling winches POCLAIN 20 Dec 1971 [22 Dec 1970 23 Nov 1971] 59125/71 Heading B8B [Also in Division F1] A device for driving the heavy piston of a subterranean pump in reciprocating motion comprises a cable 9 coupling the piston to a winch drum 10 thereabove, the drum 10 being driven by an hydraulic motor to transit forces to the piston that are alternately greater than and opposite the forces of gravity and friction acting on the piston, and lower than said forces of gravity and friction, and an hydraulic spring motor permanently connected to the drum drive motor to apply a force opposing the said forces of gravity. In the embodiment of Fig. 2, the winch drum 10 is drivable by an hydraulic motor 12 and the said opposing force is applied to the drum by an hydraulic motor 13 mechanically coupled through the drum to the motor 12. The motor 13 is coupled to high and low pressure hydraulic accumulators 15 and 17 whereby a continued force on the drum 10 opposes the gravity forces of the piston, and a two way distributer valve 20 alternately connects one line 19 from the motor 12 to the high pressure accumulator 15 and to the low pressure accumulator 17 under the control of a crank system 23 driven by the winch drum shaft 10a. Alternatively the distributer valve 20 is controlled by a rocking lever having cam arms operated by a pin on the winch drum. The other line 18 of the motor 12 is always connected to the low pressure accumulator 17 so that the motor 12 has no torque when the line 19 is connected to the accumulator 17 and the pump piston therefore descends against the lower opposing force of the motor 13, and the motor 12 has a wind up torque when the accumulator 15 is connected to the line 19 whereby the piston is lifted. Pressure relief valves 32 and a pump 28 between the hydraulic circuit and a fluid reservoir 30 permit flow into and out of the system. The hydraulic spring motor may be replaced by a simple spring motor. In the embodiment of Fig. 3 (not shown) the winch drum is replaced by two adjacent toothed wheels having parallel axes the cable being replaced by a chain passing over and engageable with the two wheels. In the embodiment of Fig. 4 the winch drum 10 is driven and has its gravity opposing force applied by an hydraulic motor 39 constituting the drive and spring motor. The motor 39 which is reversible and of variable cubic capacity is driven from an hydraulic accumulator 48 in line 51, 54 which is topped up by a pump 47, the motor 39 exhausting to a fluid reservoir 30. The cubic capacity and hence torque of the motor 39 is regulated by a lever 45 movable under control of a linkage 46 coupled to the winch drum 10. With the pump piston ready to be lifted, the lever 45 is at maximum motor capacity setting and the piston is raised, the lever 45 being correspondingly moved to reduce the motor capacity until the gravity forces of the piston reverse the motor 39, at minimum capacity setting to generate a pumping action as the piston descends. This pumping action pressurizes the accumulator 48 which acts as the hydraulic spring opposing the descending piston forces. Movement of the lever 45 is controlled by a spring centered control rod movable back and forth either by a cam rotatable with the winch drum 10, or by an hydraulic piston and cylinder arrangement controlled by fluid from a reversible pump driven by the winch motor 39.